FR2746390A1 - PROCESS FOR PREPARING CYCLODODECANONE OXIME BY PHOTONITROSATION OF CYCLODODECANE IN THE PRESENCE OF TRICHLORONITROSOMETHANE - Google Patents
PROCESS FOR PREPARING CYCLODODECANONE OXIME BY PHOTONITROSATION OF CYCLODODECANE IN THE PRESENCE OF TRICHLORONITROSOMETHANE Download PDFInfo
- Publication number
- FR2746390A1 FR2746390A1 FR9603687A FR9603687A FR2746390A1 FR 2746390 A1 FR2746390 A1 FR 2746390A1 FR 9603687 A FR9603687 A FR 9603687A FR 9603687 A FR9603687 A FR 9603687A FR 2746390 A1 FR2746390 A1 FR 2746390A1
- Authority
- FR
- France
- Prior art keywords
- trichloronitrosomethane
- cyclododecane
- photonitrosation
- cyclododecanone oxime
- oxime
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/02—Preparation of lactams
- C07D201/04—Preparation of lactams from or via oximes by Beckmann rearrangement
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C249/00—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton
- C07C249/04—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of oximes
- C07C249/06—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of oximes by nitrosation of hydrocarbons or substituted hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D225/00—Heterocyclic compounds containing rings of more than seven members having one nitrogen atom as the only ring hetero atom
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/18—Systems containing only non-condensed rings with a ring being at least seven-membered
Abstract
L'invention a pour objet un procédé de préparation de l'oxime de la cydododécanone, par photonitrosation de cydododécane en présence d'acide chlorhydrique, caractérisé en ce que l'agent nitrosant est le trichloronitrosométhane.The subject of the invention is a process for preparing the oxime of cydododecanone by photonitrosation of cydododecane in the presence of hydrochloric acid, characterized in that the nitrosating agent is trichloronitrosomethane.
Description
DESCRIPTIONDESCRIPTION
La présente invention a trait au domaine des polymères du type polyamide- The present invention relates to the field of polymers of the polyamide-type
12 obtenus par polymérisation du lauryllactame. Elle conceme plus particulièrement un procédé de préparation de I'oxime de cyclododécanone (intermédiaire réactionnel 12 obtained by polymerization of lauryllactam. It relates more particularly to a process for the preparation of cyclododecanone oxime (reaction intermediate
du lauryllactame) par photonitrosation de cyclododécane en présence de trichloroni- lauryllactame) by photonitrosation of cyclododecane in the presence of trichloroni-
trosométhane.trosomethane.
Le lauryllactame est largement utilisé en tant que monomère pour la prépa- Lauryllactam is widely used as a monomer for the preparation
ration de polyamide 12 par polymérisation. De nombreuses méthodes pour sa prépa- ration of polyamide 12 by polymerization. Many methods for its preparation
io ration sont décrites dans la littérature (voir par exemple "Procédés de Pétrochimie", io ration are described in the literature (see for example "Petrochemical processes",
tome 2, pp. 316-322, Edition Technip, 1986). volume 2, pp. 316-322, Technip Edition, 1986).
Les procédés industriels les plus connus sont ceux qui ont été développés The best known industrial processes are those that have been developed
par Huils et Ato Chimie à partir de cyclododécane, Snia Viscosa à partir de mono- by Huils and Ato Chimie from cyclododecane, Snia Viscosa from mono-
ozonide du cyclododécatriène, et UBE à partir de cyclododécanone. cyclododecatriene ozonide, and UBE from cyclododecanone.
Plus précisément, on obtient le lauryllactame selon le procédé proposé par Ato Chimie en deux étapes: More specifically, the lauryllactam is obtained according to the process proposed by Ato Chimie in two stages:
- dans la première étape, on forme l'oxime de la cyclododécanone par pho- - in the first stage, the oxime of cyclododecanone is formed by pho-
tonitrosation du cyclododécane selon la réaction suivante: --CH + CINO + HCI hv N-OH, 2 HCI tonitrosation of the cyclododecane according to the following reaction: --CH + CINO + HCI hv N-OH, 2 HCI
( (CH2 (2)11((CH2 (2) 11
-et, dans la deuxième étape, I'oxime ainsi formée est soumise à une trans- -and, in the second step, the oxime thus formed is subjected to a trans-
position de Beckmann en présence d'acide sulfurique Beckmann's position in the presence of sulfuric acid
--C:N-OH, 2 HCI + H2SO4 *CO + 2 HC--C: N-OH, 2 HCI + H2SO4 * CO + 2 HC
/' 2 NiH/ '2 NiH
(CH2)11 2)11(CH2) 11 2) 11
Dans la première étape, on réalise la photonitrosation en présence de chlorure de nitrosyle, lequel composé s'avère être également un agent chlorant du In the first step, photonitrosation is carried out in the presence of nitrosyl chloride, which compound turns out to be also a chlorinating agent of
cyclododécane. On forme ainsi des sous-produits chlorés, tels que des chloroalca- cyclododecane. In this way chlorinated by-products are formed, such as chloroalca-
nes et des chloro-oximes. De tels composés, non valorisables, sont préjudiciables -2- aussi bien au rendement et à la sélectivité de la réaction qu'à la qualité du produit nes and chloro-oximes. Such compounds, which cannot be reused, are detrimental to both the yield and the selectivity of the reaction and to the quality of the product.
final et doivent donc être éliminés par le biais de purifications longues et coûteuses. final and must therefore be eliminated through long and costly purifications.
Il a maintenant été trouvé que l'emploi de trichloronitrosométhane comme agent nitrosant permet, tout en gardant les avantages liés à la photonitrosation, d'améliorer la sélectivité en prévenant la formation de sous-produits chlorés précités. L'invention a donc pour objet un nouveau procédé de préparation de l'oxime de la cyclododécanone, par photonitrosation de cyclododécane en présence d'acide It has now been found that the use of trichloronitrosomethane as a nitrosating agent makes it possible, while retaining the advantages linked to photonitrosation, to improve selectivity by preventing the formation of the abovementioned chlorinated by-products. The subject of the invention is therefore a new process for the preparation of cyclododecanone oxime, by photonitrosation of cyclododecane in the presence of acid
chlorhydrique, caractérisé en ce que l'agent nitrosant est le trichloronitrosométhane. hydrochloric, characterized in that the nitrosating agent is trichloronitrosomethane.
Le trichloronitrosométhane du procédé selon l'invention est généralement io formé à partir de chlorure de nitrosyle et de chloroforme par réaction photochimique conventionnelle, par exemple dans un réacteur comportant des lampes à vapeur de mercure ou de sodium. La réaction photochimique est généralement effectuée à une The trichloronitrosomethane of the process according to the invention is generally formed from nitrosyl chloride and chloroform by conventional photochemical reaction, for example in a reactor comprising mercury or sodium vapor lamps. The photochemical reaction is generally carried out at a
température comprise entre 10 et 20 C, à la pression atmosphérique. La concentra- temperature between 10 and 20 C, at atmospheric pressure. The concentration
tion en poids de chlorure de nitrosyle dans le chloroforme est de préférence com- tion by weight of nitrosyl chloride in chloroform is preferably com-
prise entre 2 et 10 g/I.taken between 2 and 10 g / I.
On utilise le trichloronitrosométhane sous forme d'une solution dans les Trichloronitrosomethane is used in the form of a solution in the
solvants chlorés, de préférence le chloroforme. chlorinated solvents, preferably chloroform.
La concentration en poids de trichloronitrosométhane dans le solvant précité The concentration by weight of trichloronitrosomethane in the abovementioned solvent
est généralement comprise entre 0,2 et 20 g/I et de préférence entre 8 et 12 g/i. is generally between 0.2 and 20 g / I and preferably between 8 and 12 g / i.
L'acide chlorhydrique est généralement mis en oeuvre sous forme d'acide Hydrochloric acid is generally used in the form of acid
chlorhydrique gazeux et anhydre.hydrochloric gas and anhydrous.
Le cyclododécane peut être obtenu selon des méthodes connues de Cyclododecane can be obtained by known methods of
l'homme du métier, par exemple par cyclotrimérisation du butadiène et hydrogéna- a person skilled in the art, for example by cyclotrimerization of butadiene and hydrogenation
tion du cyclododécatriène formé.tion of the cyclododecatriene formed.
Le procédé selon l'invention est mis en oeuvre par transformation directe du The method according to the invention is implemented by direct transformation of the
mélange constitué par le cyclododécane, I'acide chlorhydrique et le trichloronitroso- mixture consisting of cyclododecane, hydrochloric acid and trichloronitroso-
méthane dans des conditions photochimiques conventionnelles. methane under conventional photochemical conditions.
Dans le but de faciliter l'extraction de l'oxime lors de la phase ultérieure de décantation, on ajoute avantageusement au mélange une faible quantité d'acide In order to facilitate the extraction of the oxime during the subsequent decantation phase, a small amount of acid is advantageously added to the mixture.
sulfurique dont le titre est compris entre 75 et 98 % en poids. sulfuric acid with a titer between 75 and 98% by weight.
Le mélange est généralement irradié à une température comprise entre 0 et C au moyen de lampe(s) à vapeur de mercure ou de sodium émettant entre 400 The mixture is generally irradiated at a temperature between 0 and C by means of mercury or sodium vapor lamp (s) emitting between 400
et 600 nm et de préférence 500 et 600 nm. and 600 nm and preferably 500 and 600 nm.
Le procédé selon l'invention est généralement mis en oeuvre à la pression The process according to the invention is generally carried out under pressure
atmosphérique.atmospheric.
A l'issue de la réaction, on soumet le mélange à une décantation et on récu- After the reaction, the mixture is decanted and recovered
père l'oxime de la cyclododécanone dans la phase aqueuse. father the cyclododecanone oxime in the aqueous phase.
-3- L'oxime ainsi formée peut être utilisée pour la préparation du lauryllactame, -3- The oxime thus formed can be used for the preparation of lauryllactam,
par exemple par transposition de Beckmann en présence d'acide sulfurique. for example by transposition of Beckmann in the presence of sulfuric acid.
Les exemples suivants illustrent l'invention sans toutefois la limiter. The following examples illustrate the invention without, however, limiting it.
EXEMPLEEXAMPLE
On utilise un réacteur photochimique équipé d'un porte-lampe central à im- A photochemical reactor equipped with a central lamp holder with im-
mersion et d'une lampe à vapeur de sodium à moyenne pression de 250 Watts émettant un maximum de radiations au voisinage de 595 nm. Le porte- lampe et la mersion and a 250 watt medium pressure sodium vapor lamp emitting a maximum of radiation near 595 nm. The lamp holder and the
lampe sont thermostatés par une circulation d'eau à 15 C. lamps are thermostatically controlled by a water circulation at 15 C.
Ainsi équipé, le réacteur a un volume utile de 250 ml et la lampe présente un Thus equipped, the reactor has a useful volume of 250 ml and the lamp has a
trajet optique égal à 6,5 mm.optical path equal to 6.5 mm.
L'introduction des réactifs est réalisée à la pression atmosphérique au moyen d'une tubulure équipée d'un fritté (porosité 4) située dans la partie inférieure The reagents are introduced at atmospheric pressure by means of a tube fitted with a sinter (porosity 4) located in the lower part
du réacteur.of the reactor.
Les effluents gazeux issus du réacteur sont, après circulation dans un dis- The gaseous effluents from the reactor are, after circulation in a
positif réfrigéré (température 0 C), dirigés vers un barboteur contenant une solution positive refrigerated (temperature 0 C), directed to a bubbler containing a solution
de soude relié à une torche.of soda connected to a torch.
a) préparation du trichloronitrosométhane Dans le réacteur, on introduit 200 ml de chloroforme dans lequel on dissout progressivement le chlorure de nitrosyle jusqu'à ce que la concentration soit égale à 2 g/I. On allume la lampe et on irradie pendant 3 heures tout en maintenant un débit a) preparation of trichloronitrosomethane 200 ml of chloroform are introduced into the reactor, in which the nitrosyl chloride is gradually dissolved until the concentration is equal to 2 g / l. We turn on the lamp and irradiate for 3 hours while maintaining a flow
constant de 2 I/h en chlorure de nitrosyle. constant of 2 I / h in nitrosyl chloride.
Après extinction de la lampe et arrêt de l'injection de chlorure de nitrosyle, on After switching off the lamp and stopping the injection of nitrosyl chloride,
place le mélange obtenu sous un courant d'azote afin d'éliminer le chlorure de nitro- place the mixture obtained under a stream of nitrogen in order to remove the nitro chloride
syle qui n'a pas réagi. On observe alors l'apparition d'une couleur bleue caractérisfti- syle that did not react. We then observe the appearance of a characteristic blue color.
que du trichloronitrosométhane (présence d'une bande à 592 nm; s: 5,57 mole-1. than trichloronitrosomethane (presence of a band at 592 nm; s: 5.57 mole-1.
litre. cm-1).liter. cm-1).
La concentration en trichloronitrosométhane dans le chloroforme est égale à g/I. b) photonitrosation du cyclododécane La solution chloroformique de trichloronitrosométhane précitée, à laquelle on ajoute 25 ml d'acide sulfurique à 85 %, 2 g d'acide chlorhydrique gazeux et 17 g de cyclododécane, est irradiée pendant 90 minutes sous agitation au moyen d'une The concentration of trichloronitrosomethane in chloroform is equal to g / I. b) photonitrosation of cyclododecane The abovementioned chloroformic solution of trichloronitrosomethane, to which 25 ml of 85% sulfuric acid, 2 g of gaseous hydrochloric acid and 17 g of cyclododecane are added, is irradiated for 90 minutes with stirring using a
pompe (renouvellement du volume du réacteur: 100 fois par heure). pump (reactor volume renewal: 100 times per hour).
A l'issue de la réaction, le mélange obtenu, qui a perdu sa couleur bleue, est décanté. -4- La phase aqueuse récupérée contient 2,59 g d'oxime de la cyclododécanone At the end of the reaction, the mixture obtained, which has lost its blue color, is decanted. -4- The aqueous phase recovered contains 2.59 g of cyclododecanone oxime
(soit un rendement de 97,7 % calculé sur la base du trichloronitrosométhane enga- (i.e. a yield of 97.7% calculated on the basis of the trichloronitrosomethane enga-
gé) et aucune chloro-oxime.ge) and no chloro-oxime.
La phase organique résiduelle ne contient pas de dérivé chloré du cyclodo- The residual organic phase does not contain a chlorinated derivative of cyclodo-
décane de départ.decane of departure.
EXEMPLE COMPARATIFCOMPARATIVE EXAMPLE
On opère dans le réacteur décrit à l'exemple précédent, l'agent nitrosant uti- One operates in the reactor described in the previous example, the nitrosating agent used
lisé étant le chlorure de nitrosyle. read being nitrosyl chloride.
Dans le réacteur contenant 200 ml d'une solution de cyclododécane dans le chloroforme (300 g/I) et 20 ml d'acide sulfurique à 85 % en poids, on injecte en continu du chlorure de nitrosyle gazeux de telle sorte que, après l'allumage de la In the reactor containing 200 ml of a solution of cyclododecane in chloroform (300 g / I) and 20 ml of 85% by weight sulfuric acid, gaseous nitrosyl chloride is injected continuously so that, after 1 ignition
lampe, la concentration dans le milieu réactionnel soit égale à 2 g/I. lamp, the concentration in the reaction medium is equal to 2 g / I.
Le milieu réactionnel, agité au moyen d'une pompe externe (renouvellement The reaction medium, stirred by means of an external pump (renewal
du volume du réacteur: 100 fois par heure) est irradié pendant 2 heures. of the reactor volume: 100 times per hour) is irradiated for 2 hours.
A l'issue de la réaction, le mélange réactionnel est décanté. At the end of the reaction, the reaction mixture is decanted.
Dans la phase aqueuse, on récupère l'oxime de la cyclododécanone In the aqueous phase, the cyclododecanone oxime is recovered
(sélectivité molaire: 88,35 %) ainsi que des chloro-oximes (5,4 % en poids du mé- (molar selectivity: 88.35%) as well as chloro-oximes (5.4% by weight of the
lange). La phase organique contient, outre le cyclododécane résiduel, des dérivés mono- et dichlorés du cyclododécane respectivement 4,95 et 1,65 % en poids du diaper). The organic phase contains, in addition to the residual cyclododecane, mono- and dichlorinated derivatives of cyclododecane respectively 4.95 and 1.65% by weight of the
cyclododécane de départ.starting cyclododecane.
-5--5-
Claims (7)
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9603687A FR2746390B1 (en) | 1996-03-25 | 1996-03-25 | PROCESS FOR PREPARING CYCLODODECANONE OXIME BY PHOTONITROSATION OF CYCLODODECANE IN THE PRESENCE OF TRICHLORONITROSOMETHANE |
| DE69701297T DE69701297T2 (en) | 1996-03-25 | 1997-03-14 | Process for the preparation of the oxime of cyclododecanone by photonitrosation of cyclododecane in the presence of trichloronitrosomethane |
| EP97400568A EP0798290B1 (en) | 1996-03-25 | 1997-03-14 | Process for the preparation of the oxim of cyclododecanone by photonitrosation of cyclododecane in the presence of trichloronitrosomethane |
| KR1019970008784A KR100204133B1 (en) | 1996-03-25 | 1997-03-14 | Process for the preparation of the oxim of cyclododecanone by photonitrosation of cyclodedecane inthe presence of trichloronitrosomethane |
| CN97104507A CN1063171C (en) | 1996-03-25 | 1997-03-18 | Process for preparation of lauryllactam by photonitrosation of cyclododecane in presence of trichloronitrosomethane |
| JP9088914A JP2945350B2 (en) | 1996-03-25 | 1997-03-24 | Process for producing lauryl lactam by photonitrosation of cyclododecane in the presence of trichloronitrosomethane |
| CA002200892A CA2200892C (en) | 1996-03-25 | 1997-03-24 | Process for preparing lauryllactam through photonitrosation of cyclododecane in the presence of trichloronitrosomethane |
| US08/822,488 US5719316A (en) | 1996-03-25 | 1997-03-24 | Process for the preparation of lauryllactam by photonitrosation of cyclododecane in the presence of trichloronitrosomethane |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9603687A FR2746390B1 (en) | 1996-03-25 | 1996-03-25 | PROCESS FOR PREPARING CYCLODODECANONE OXIME BY PHOTONITROSATION OF CYCLODODECANE IN THE PRESENCE OF TRICHLORONITROSOMETHANE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| FR2746390A1 true FR2746390A1 (en) | 1997-09-26 |
| FR2746390B1 FR2746390B1 (en) | 1998-04-24 |
Family
ID=9490509
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| FR9603687A Expired - Fee Related FR2746390B1 (en) | 1996-03-25 | 1996-03-25 | PROCESS FOR PREPARING CYCLODODECANONE OXIME BY PHOTONITROSATION OF CYCLODODECANE IN THE PRESENCE OF TRICHLORONITROSOMETHANE |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5719316A (en) |
| EP (1) | EP0798290B1 (en) |
| JP (1) | JP2945350B2 (en) |
| KR (1) | KR100204133B1 (en) |
| CN (1) | CN1063171C (en) |
| CA (1) | CA2200892C (en) |
| DE (1) | DE69701297T2 (en) |
| FR (1) | FR2746390B1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100530730B1 (en) * | 1997-07-02 | 2005-11-23 | 아르끄마 | Process for the preparation of cyclododecanone oxime by photonitrosation of cyclododecane in chloroform in quasi-anhydrous medium |
| DE19813354A1 (en) | 1998-03-26 | 1999-09-30 | Bayer Ag | Arylphenyl substituted cyclic ketoenols |
| FR2784103B1 (en) * | 1998-09-21 | 2000-12-08 | Atochem Elf Sa | PROCESS FOR PREPARING LAURYLLACTAM BY PHOTONITROSATION OF CYCLODODECANE AND TRANSPOSITION OF BECKMANN IN THE PRESENCE OF METHANESULPHONIC ACID |
| JP5042434B2 (en) * | 2002-03-07 | 2012-10-03 | 株式会社ダイセル | Method for producing oxime compounds using nitrite, etc. |
| JP5359063B2 (en) * | 2008-06-30 | 2013-12-04 | 東レ株式会社 | Method for producing cycloalkanone oxime |
| JP5359064B2 (en) * | 2008-06-30 | 2013-12-04 | 東レ株式会社 | Method for producing cycloalkanone oxime and photochemical reaction apparatus |
| ES2501665T3 (en) | 2011-10-14 | 2014-10-02 | Allnex Ip S.À.R.L. | Procedure to prepare (meth) urethane acrylates of low viscosity, dilutable with water |
| ES2526796T3 (en) * | 2012-06-26 | 2015-01-15 | Toray Industries, Inc. | Cycloalcanone oxime production method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1136747A (en) * | 1965-04-21 | 1968-12-18 | Basf Ag | Continuous photooximation of cyclododecane |
| DE2001331A1 (en) * | 1969-01-13 | 1970-07-23 | Mobil Oil Corp | Process for the preparation of ketoximes |
| FR2094612A5 (en) * | 1970-06-26 | 1972-02-04 | Aquitaine Total Organico | Photo-oximation of higher cycloalkanes - without using a solvent |
-
1996
- 1996-03-25 FR FR9603687A patent/FR2746390B1/en not_active Expired - Fee Related
-
1997
- 1997-03-14 DE DE69701297T patent/DE69701297T2/en not_active Expired - Fee Related
- 1997-03-14 KR KR1019970008784A patent/KR100204133B1/en not_active IP Right Cessation
- 1997-03-14 EP EP97400568A patent/EP0798290B1/en not_active Expired - Lifetime
- 1997-03-18 CN CN97104507A patent/CN1063171C/en not_active Expired - Fee Related
- 1997-03-24 US US08/822,488 patent/US5719316A/en not_active Expired - Fee Related
- 1997-03-24 JP JP9088914A patent/JP2945350B2/en not_active Expired - Lifetime
- 1997-03-24 CA CA002200892A patent/CA2200892C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1136747A (en) * | 1965-04-21 | 1968-12-18 | Basf Ag | Continuous photooximation of cyclododecane |
| DE2001331A1 (en) * | 1969-01-13 | 1970-07-23 | Mobil Oil Corp | Process for the preparation of ketoximes |
| FR2094612A5 (en) * | 1970-06-26 | 1972-02-04 | Aquitaine Total Organico | Photo-oximation of higher cycloalkanes - without using a solvent |
Non-Patent Citations (2)
| Title |
|---|
| B.C. GOWENLOCK ET AL, TETRAHEDRON LETT., no. 7, 1972, pages 593 - 596 * |
| CHEMICAL ABSTRACTS, vol. 76, no. 21, 22 May 1972, Columbus, Ohio, US; abstract no. 126097z, page 424; XP002019960 * |
Also Published As
| Publication number | Publication date |
|---|---|
| KR100204133B1 (en) | 1999-06-15 |
| EP0798290A1 (en) | 1997-10-01 |
| JPH1025279A (en) | 1998-01-27 |
| US5719316A (en) | 1998-02-17 |
| CN1163886A (en) | 1997-11-05 |
| FR2746390B1 (en) | 1998-04-24 |
| EP0798290B1 (en) | 2000-02-16 |
| CA2200892C (en) | 2001-05-22 |
| DE69701297T2 (en) | 2000-06-08 |
| CN1063171C (en) | 2001-03-14 |
| DE69701297D1 (en) | 2000-03-23 |
| CA2200892A1 (en) | 1997-09-25 |
| KR970065515A (en) | 1997-10-13 |
| JP2945350B2 (en) | 1999-09-06 |
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